Acer Aspire 1400, Service Manual

Page: 37 / 118

Chapter 1 31
3. Automatic brightness compensation for input voltage variation.
NOTE: Please pay attention to the fellowing:
*1. Limited lamp maximum current by DAC_BRIC signal:
When DAC_BRIG voltage is 0V and INV_PWM enables (100%), lamp has max. current.
When DAC_BRIG voltage is 3.3V and INV_PWM enables (100%), lamp has min. current.
DAC_BRIG signal comes from system chipset with internal resistance of 3K
Electrical Characteristics
No
.
Parameter Symbol Min. Typ. Max. Unit Conditions
1 Input
voltage
NV_PWR 9 14.8 21 V
2 Input
current
Iin -- 0.33 -- A
3
Lamp
current
IL 2.7 -- 6.6 mA *Note 1
4
Frequency
f 50
55
60KHz
KHz
* Note 2
5 Output
power Pout -- -- 4.5 W
6 Efficiency
η
80% -- -- --
7 Starting
voltage Vs 1500 -- --- V
8 Starting
time Tvs 1 -- 2 Sec
9 Dispoff# 2.8 3.3 3.6 V Backlight on/off signal
0 0.5 0.8 V Low level
10 Limited
lamp
maximum
current DAC-
BRIG 0 3.3 V *Note 1
11 PWM
signal
*Note 4 INV_PW
M 142 150 158 Hz PWM signal frequency
30 3.3 3.6 V PWM signal amplitude
40 -- 100 %
12 Lamp
current
over-shoot I zero-PK -- -- 11 mA Line transient (10.8V to
21V/100us) and turn on
transient
13 Current
Waveform
factor 1.27 1.56 Multiple or
*10
14 Unbalance
Rate -10% 0 +10% Mulitple
Duty
Ton
Period
------------------- =
rms
p
I
I
2
rms
p
I
I
−
rms
p p
I
I I
−
−
Ω